Zinc phosphate complex

ABSTRACT

An oral care composition having a soluble zinc polyphosphate complex made by combining ingredients including a zinc salt, a plurality of long chain polyphosphates having 6 or more phosphate polymer units, and a solvent, the relative amount of organic zinc salt and long chain polyphosphates provides a phosphorus to zinc mole ratio of at least 6:1. Further provided is a method of treating a subject suffering from dentinal sensitivity applying the oral care composition to the teeth and gums of the subject.

BACKGROUND

The present disclosure is directed to a soluble zinc polyphosphatecomplex for use in personal care compositions and methods of making thecomplex.

Zinc compounds are often used in oral care and personal carecompositions. Many Zinc compounds possess hydrolysis chemistry andbacteria inhibiting qualities that render them suitable for oral careproducts. For instance, zinc is considered an anti-plaque agent.Compounds such as zinc citrate and zinc oxide have been added totoothpaste to prevent plaque buildup. Zinc salts can have otherfunctions related to the body that make them desirable as activeingredients in other personal care products. For example, Zinc citrateas a trihydrate, Zn3(C6H5O7)2.3H2O, which is a white odorless powderthat is only slightly soluble in water, serves as an importantantioxidant nutrient and is vital for protein synthesis, bloodstability, normal tissue function and wound healing to name a few commonuses by the body.

Polyphosphates are known in the art for use as, for example, chelants,in oral care compositions, in addition, polyphosphates such asdiphosphate (also known as pyrophosphate) and triphosphate are known foruse as anions in antiperspirants, as taught in WO 220131013903,published on Jan. 31, 2013, Longer chain linear polyphosphates (morethan 3 phosphate units) are susceptible to hydrolysis in aqueouscompositions. Upon hydrolysis they are known to form orthophosphateswhich form insoluble zinc complexes.

Dentinal hypersensitivity (i,e, sensitivity) is a painful conditionresulting from the movement of liquid in exposed dentin tubules fromexternal stimuli such as pressure and temperature. On strategy to reduceand/or eliminate the pain resulting from exposed dentin tubules is toform insoluble precipitates in the tubules in order to physically plugthe tubules. For instance, Stannous salts have been shown to treatdentinal hypersensitivity by depositing into tubules from neat solutionsand from simple formulations, as described in U.S. Patent ApplicationPublication No, 2009/0136432, the disclosure of which is herebyincorporated by reference in its entirety.

Antiperspirant substances often employ aluminum containing actives.These substances reduce the flow of sweat by forming a plug in the sweatduct. However, due to consumer concern about aluminum basedantiperspirant products, Aluminum free antiperspirant actives are indemand.

The discovery of a novel zinc complex that can be used to treat dentinalhypersensitivity and/or that can act as an antiperspirant active wouldbe a welcome addition to the art. In addition, it would be desirable tomanipulate zinc salt structures in efforts to enhance efficacy andextend the applications of these compounds in oral care and personalcare products.

BRIEF SUMMARY

An embodiment of the present disclosure is directed to an oral carecomposition, comprising: a soluble zinc polyphosphate complex made bycombining ingredients comprising an organic zinc salt, a plurality oflong chain polyphosphates having 6 or more phosphate polymer units, anda solvent; wherein the relative amount of organic zinc salt and longchain polyphosphates provides a phosphorus to zinc mole ratio of atleast 6:1.

In another embodiment, the present disclosure is directed to a method oftreating a subject suffering from dentinal sensitivity, the methodcomprising: providing an oral care composition comprising a soluble zincpolyphosphate complex made by combining ingredients comprising anorganic zinc salt, a plurality of long chain polyphosphates having 6 ormore phosphate polymer units, and a solvent; and applying the oral carecomposition to the teeth and gums of the subject in an amount that isefficacious for treating dentinal sensitivity; wherein the relativeamount of organic zinc salt and long chain polyphosphates provides aphosphorus to zinc mole ratio of at least 6:1.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the disclosure, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

As used throughout, ranges are used as shorthand for describing each andevery value that is within the range. Any value within the range can beselected as the terminus of the range. In addition, all references citedherein are hereby incorporated by referenced in their entireties. In theevent of a conflict in a definition in the present disclosure and thatof a cited reference, the present disclosure controls.

Unless otherwise specified, all percentages and amounts expressed hereinand elsewhere in the specification should be understood to refer topercentages by weight. The amounts given are based on the active weightof the material.

An embodiment of the present disclosure is directed to a soluble zincpolyphosphate complex. The complex is made by combining ingredientscomprising an organic zinc salt, a plurality of long chainpolyphosphates having 6 or more phosphate polymer units and an aqueoussolvent. The relative amount of organic zinc salt and long chainpolyphosphates provides a phosphorus to zinc mole ratio of at least 6:1,such as about 15:1 to about 25:1.

In certain embodiments, the zinc polyphosphate complex has the propertyof reduced solubility in water at a first condition of 37° C. and a pHof about 7.4 in the presence of 1% by weight Bovine Serum Albuminprotein when compared with a second condition of 25° C.: and a pH of 5.4in the absence of protein. The reduction in solubility is sufficient toallow a desired amount of the soluble zinc polyphosphate complex in asaturated solution at the second condition to precipitate from thesaturated solution at the first condition.

Any suitable organic zinc ion source can be used to form the zinccomplexes of the present disclosure. Examples of suitable organic zincsalts include zinc lactate, zinc citrate, zinc acetate, zinc gluconate,zinc malate, zinc tartrate and combinations thereof Any of the organiczinc salts may or may not be in a hydrate form. For example, zinccitrate can be in a tryhydrated form (e.g., Zn₃(C.₆H₅O₇)₂.3H₂0). Thususe of organic zinc precursors results in an organic ligand beingpresent in the resulting complex.

Any polyphosphates having 6 or more phosphate polymer units can beemployed to form the zinc complexes of the present disclosure. In anembodiment, long chain polyphosphate having about 6 to about 50phosphate polymer units, such as 6 to about 30 phosphate polymer units,can be used. An example of a long chain polyphosphate is sodiumhexametaphosphate (“SHMP”),

The phosphorus to zinc mole ratio can be any mole ratio of at least 6:1that results in a soluble complex at the desired pH in an aqueoussolution. In an embodiment, the phosphorus to zinc mole ratio rangesfrom about 10:1 to about 55:1, such as about 12:1 to about 40:1, orabout 15:1 to about 25:1, about 18:1 to about 23:1, or about 20:1 toabout 23:1.

The amount of zinc ion source to phosphate polymer reactant employedwill vary depending on the desired phosphorus to zinc mole ratio and theparticular reactants used. For example, a mole ratio range of about 15:1to about 25:1 P to Zn mole ratio corresponds to about 5.5:1 to about 9.2to 1 weight ratio of SHMP:ZnLac while having about a 2,5% wily ZnLacconcentration.

In an embodiment, the resulting; zinc polyphosphate complex has anaverage of 15 or more P atoms. For example, the zinc polyphosphatecomplex can have an average of about 18 to about 25 P atoms, such asabout 20 to 23 P atoms. In an embodiment, zinc polyphosphate complexformed in the composition has an average of about 1 zinc atom.

In an embodiment, the zinc polyphosphate complex has a property ofbecoming insoluble in aqueous solution at a pH ranging from 5.5 orabove, such as above 7 to about 7.5 or higher, depending on theparticular organic salt used to form the complex. The zinc polyphosphatecomplex can also have the property of being insoluble, at a pH below 7in aqueous solution in the presence of proteins, such as salivaryproteins or skin proteins. The protein can be introduced during use, forexample from the saliva, skin, or perspiration of a user. The amount ofprotein will vary depending on the conditions of use and can be anysuitable amount that aids in triggering precipitation, such as, forexample, about 0.1% by weight or more, or about 0.5% by weight or more,such as about 1% by weight.

When used in an oral care product, the soluble zinc and polyphosphatecomplexes of the present disclosure can remain soluble in compositionuntil introduced into the oral cavity of a patient, at which point thecomplexes precipitate on biomaterial surfaces such as in dentinaltubules. For example, the soluble zinc polyphosphate complex can diffuseinto dentinal tubules and precipitate, to thereby physically occlude thedentinal tubules and prevent dentinal hypersensitivity. In addition, inthe presence of protein the zinc precipitate can have relatively strongacid resistance. Such protein can come, for example, from the saliva ofa user, or can be added to the composition. Based on the results of thedata, the new zinc complex is a potential candidate for among otherthings, toothpastes for dentinal hypersensitivity relief.

Thus, the aqueous zinc polyphosphate complexes of the present disclosurecan have one or more of the following advantages: the ability to remainsoluble at pH below 7, such as below 5.5, the ability to precipitate ata pH above 5.5, such as above 7, the ability to occlude dentin tubulesand relieve or eliminate dentinal hypersensitivity; the ability to formprecipitates that remain insoluble at a pH below 7 in the presence ofsalivary proteins; the ability to in situ generate a precipitate uponinteraction with saliva to effectively deliver zinc to the oral surfaceand provide dentin sensitivity relief, antimicrobial function, or anyother benefit that may become apparent; the ability to in situ generatea precipitate upon interaction with skin proteins; or the ability toprovide antimicrobial and/or anti-inflammatory effects when applied in apersonal care product, such as deodorants or antiperspirants. Thus, thiscomplex has high potential in the oral care and personal care fields.

The present disclosure is also directed to a method of making a solublezinc polyphosphate complex. The method comprises combining organic zincsalt; a plurality of long chain polyphosphates having 4 or morephosphate polymer units; and an aqueous solvent. As discussed above, therelative amount of organic zinc salt and long chain polyphosphatesprovides a phosphorus to zinc mole ratio of at least 6:1. Theingredients can be mixed in any suitable order and using any suitablemixing technique with or without heating, so long as the method resultsin the formation of the desired soluble zinc polyphosphate complex.

In certain embodiments, the solvent used in the method is at least onesolvent chosen from water, glycerin, diglycerol (glycerol-2),triglycerol (glycerol-3), quadraglycerol (glycerol-4), sorbitol, andpolyethylene glycol having a weight average molecular weight less than10,000. In one embodiment, the solvent is water. In one embodiment, theamount of solvent is 40 to 90 weight % based on a total weight oforganic zinc salt, polyphosphate, and solvent. In other embodiments, theamount of solvent is 70 to 90 weight %, 75 to 85 weight %, or about 80weight %.

Oral Care Compositions

The present disclosure is also directed to an oral care composition. Thecomposition comprises a soluble zinc polyphosphate complex made bycombining ingredients comprising an organic zinc salt, a plurality oflong chain polyphosphates having 6 or more phosphate polymer units, andan aqueous solvent. The relative amount of organic zinc salt and longchain polyphosphates provides a phosphorus to zinc mole ratio of atleast 6:1, such as at least 10:1, at least 12:1, at least 15:1, or atleast 18;1, such as about 20:1; and wherein the zinc polyphosphatecomplex has increased solubility at a pH below 7.

The target amount of zinc to precipitate in the oral care compositioncan be any amount that will reduce dentinal hypersensitivity to adesired degree. In an embodiment, the amount is about 0.1 or more, suchas about 0.1 to about 0.5, or about 0.3 to about 0.4. Suitable amountsof soluble zinc complex can be provided in the oral composition toachieve the desired target precipitate during use.

The oral compositions may be provided in an orally acceptable carrier orvehicle. The carrier can be a liquid, semi-solid, or solid phase, in theform of a mouth rinse or mouth wash, dentifrice (including toothpastes,toothpowders, and prophylaxis pastes), confectionaries (includinglozenges and gum), medicament, film, or any other form known to one ofskill in the art. Selection of specific carrier components is dependenton the desired product form.

In various embodiments, the oral composition has an orally acceptablevehicle that has a pH of about 6 to 10, or about 7 to 9. Certaincomponents serve to raise the pH of the oral composition. Such compoundsinclude conventional buffers and salts, as well as chemicals such as theanionic linear polycarboxylates (described above) and polyacrylates suchas those available from B.F. Goodrich of Cleveland, Ohio sold under thetrade name CARBOPOL® have been observed to raise pH when present in oralcompositions.

Conventional ingredients can be used to form the carriers listed above.The oral compositions may include other materials in addition to thosecomponents previously described, including for example, surface activeagents, such as surfactants, emulsifiers, and foam modulators, viscositymodifiers and thickeners, humectants, diluents, additional pH modifyingagents, emollients, moisturizers, mouth feel agents, sweetening agents,flavor agents, colorants, preservatives, solvents, such as water andcombinations thereof. Any given material may serve multiple purposeswithin two or more of such categories a materials. Preferably, suchcarrier materials are selected for compatibility and stability with allof the constituents of the active ingredient.

Useful surface active agents are known in the art, such as thosedisclosed in U.S. Pat. No. 4,894,220, the disclosure of which isincorporated herein by reference in its entirety. Surface active agentscan function as surfactants, emulsifiers foam modulators, and/or activeingredient dispersion agents.

Suitable surface active agents are those that are reasonably stable andfoam throughout a wide range. These compounds are known in the art, andinclude non-soap anionic (e.g., sodium lauryl sulfate (SLS),N-myristoyl, and N-palmitoyl sarcosine), nonionic (e.g., Polysorbate 20(polyoxyethylene 20 sorbitan monolaurate, TWEEN® 20) and Polysorbate 80(polyoxyethylene 20 sorbitan monooleate, TWEEN® 803, Poloxamer 407,available under the trade name PLURONIC® F127 from BASF Corporation),cationic, zwitterionic (e.g., cocoamidopropyl betaine and lauramidopropyl betaine), and amphoteric organic synthetic detergents. In variousembodiments, one or more surface active agents are present in the oralcomposition in the range of about 0.001% to about 5%, or about 0.5% toabout 2.5%. In embodiments where the oral composition comprises anactive ingredient comprising lipophilic active compound(s), the amountof surface active agent can be increased to enable sufficientemulsification of the active ingredients within the carrier of the oralcomposition. The carrier can be, for example, an aqueous carrier.

In an embodiment, the zinc salts of the present disclosure can be usedin translucent aqueous formulations, such as mouthrinse. In embodimentswhere the oral composition is in the form of a mouthrinse, an exemplarycarrier is substantially liquid. The term “mouthrinse” includesmouthwashes, sprays and the like. In such a preparation the orallyacceptable carrier typically has an aqueous phase comprising eitherwater, or a water and alcohol mixture. Further, in various embodiments,the oral carrier can comprise, for example, a humectant, surfactant, anda pH buffering agent.

The oral composition may optionally comprise a flavoring, agent.Exemplary flavoring substances are known to a skilled artisan, and maybe present in certain embodiments at a concentration of about 0.05% byweight to about 5% by weight.

In embodiments where an oral composition is in the form of aconfectionary, an exemplary carrier may be substantially solid orsemi-solid. Confectionary carriers are known in the art. For a lozenge,the carrier can comprise, for example, a lozenge base material (forexample, comprising a non-cariogenic polyol and/or starch/sugarderivative), an emulsifier, a lubricant, a flavoring agent, a thickener,and optionally a coating material. Chewing gum carriers generally have achewing gum base, one or more plasticizing agents, a sweetening agent,and a flavoring agent.

In embodiments where an oral composition is in the form of a film, anexemplary carrier is substantially solid or semi-solid. Such filmcarriers can comprise, for example, a water soluble or dispersible filmforming agent, such as a hydrophilic polymer. Optionally, the filmcarrier may also comprise hydrophobic film forming polymers, either as aremovable backing layer, or mixed with a hydrophilic film formingpolymer. Film carriers optionally comprise plasticizers, surface activeagents, fillers, bulking agents, and viscosity modifying agents.

In embodiments where an oral composition is in the form of a dentifrice,an exemplary carrier is substantially semi-solid or a solid. Dentifricescan comprise, for example, surface active agents, humectants, viscositymodifying agents and/or thickeners, abrasives, solvents, such as water,flavoring agents, and sweetening agents.

In embodiments an oral composition is in the form of a medicament, suchas a non-abrasive gel or ointment that can be applied to the gingivalsulcus or margin and can be used in conjunction with wound dressings,gauze, films, and the like. Such gels may include both aqueous andnon-aqueous gels. Aqueous gels generally comprise a polymer base, athickener, a humectant, a flavoring agent, a sweetening agent, and asolvent, typically including water.

In various embodiments, the compositions and methods of the presentdisclosure promote oral health in an oral cavity and treat plaque on anoral surface of a mammalian subject. In one embodiment, a method ofproviding one or more oral health benefits to an oral cavity of amammalian subject entails preparing an oral composition as describedherein, where an active ingredient comprises any of the soluble zincpolyphosphate complexes disclosed herein. The prepared oral compositionis contacted with an oral surface within an oral cavity. In addition totreating dentinal hypersensitivity, compositions of the presentdisclosure containing the active ingredient may provide multiple oralhealth and body health benefits, such as anti-gingivitis,anti-periodontitis, anti-caries, anti-tartar, anti-microbial,anti-inflammatory, analgesic, anti-aging, and breath freshening. Severalof these benefits can be advantages in personal care products other thanoral compositions. Such personal care products are described in greaterdetail below.

Thus, an of the Various embodiments of the oral care compositiondescribed above are contacted with or applied regularly to an oralsurface, such as at least one time a day, or on multiple days in a week.

The oral composition of the present invention can be made by any of themethods known in the art for combining ingredients to make oral carecompositions. Methods for making the oral compositions comprising asoluble zinc polyphosphate complex, as described herein, are well withinthe ordinary skill of the art.

Personal Care Compositions

he compositions of the present disclosure can be used in personal carecomposition. Examples of such compositions include, but are not limitedto, antiperspirants, deodorants, body washes, shower gels, bar soaps,shampoo, hair conditioners and cosmetics.

For antiperspirant and/or deodorant compositions, the carrier can be ancarrier that is used for antiperspirants and/or deodorants. The carriercan be in the form of a stick, a gel, a roll-on or an aerosol. For stickformulations, the carrier may include oils and/or silicones and gellingagents. An example of a formulation can be found in US2011/0076309A1,which is incorporated herein by reference in its entirety.

In an embodiment, the personal care compositions, such asantiperspirants and/or deodorants, include a soluble zinc polyphosphatecomplex made by combining ingredients comprising an organic zinc salt, aplurality of long chain polyphosphates having 6 or more phosphatepolymer units, and an aqueous solvent. The relative amount of organiczinc salt and long chain polyphosphates provides a phosphorus to zincmole ratio is at least 6:1, such as at least 10:1, at least 12:1, atleast 15:1, or at least 18:1, such as about 20:1; and can be any of theother phosphorus to zinc mole ratios taught herein for the soluble zincpolyphosphate complex.

The amount of zinc in a personal care composition can be any suitableeffective amount. Suitable amounts of zinc can range, for example, fromabout 0.2% by weight or more, such as about 0.5% to about 10% by weight,relative to the total weight of the composition.

As described above, the zinc polyphosphate complex has the property ofreduced solubility in water at certain temperature and pH conditions,but is soluble at other conditions. In an embodiment, the formulationcan be formulated without added protein, such as BSA. The proteindesired to trigger precipitation can be provided by the sweat of theuser after application of the product.

In an embodiment, the zinc polyphosphate complex ran have reducedsolubility at for example, a condition of 37° C. and a pH of about 7.4in the presence of 1% by weight Bovine Serum Albumin protein whencompared with a second condition of 25° C. and a pH of 5.4 in theabsence of protein. The reduction in solubility can be sufficient toallow a desired amount of the soluble zinc polyphosphate complex in asaturated solution at the second condition to precipitate from thesaturated solution at the first condition, as described above.

In an embodiment, the protein can also be used to enhance the efficacyof other antiperspirant salts comprising a polyvalent cation, forexample antiperspirant complexes of (i) aluminum and optionallyzirconium, (ii) chlorohydrate, and (iii) optionally an ammo acid and/orammonium acid, for example glycine and/or trimethylglycine, e.g.,aluminum zirconium tetrachlorohydrex glycine. In an embodiment, theseother antiperspirant salts can be added to the formulations of thepresent disclosure in addition to the zinc polyphosphate complexantiperspirant. In an alternative embodiment, the formulation includesonly very small amounts or is entirely or substantially free of theabove aluminum or zirconium antiperspirant active complexes. Forexample, the formulations can include less than 2 wt %, or less than 0.5wt %, or less than 0.1 wt. %, or less than 0.01 wt. %, or less than0.001 wt. or less than 0.0001 wt. % aluminum or zirconium, relative tothe total weight of the formulation.

The present disclosure thus provides antiperspirant products comprisinga zinc polyphosphate complex antiperspirant active, e.g., any of thezinc polyphosphate complexes discussed herein, as well as methods ofmaking and using such products. The disclosure further provides methodsof reducing sweat and/ or odor comprising applying the composition toskin, and methods of killing bacteria comprising contacting the bacteriawith the composition.

Optional ingredients that can be included in an antiperspirant and/ ordeodorant formulations of the present disclosure include solvents;water-soluble alcohols such as C₂₋₈ alcohols including ethanol; glycolsincluding propylene glycol, dipropylene glycol, tripropylene glycol andmixtures thereof; glycerides including mono-, di- and triglycerides;medium to long chain organic acids, alcohols and esters; surfactantsincluding emulsifying and dispersing agents; amino acids includingglycine; structurants including thickeners and gelling agents, forexample polymers, silicates and silicon dioxide; emollients; fragrances;and colorants including dyes and pigments. If desired, an antiperspirantand/or deodorant agent additional to the soluble zinc polyphosphatecomplex can be included, for example an odor reducing agent such as asulfur precipitating agent, e,g., copper gluconate, zinc gluconate, zinccitrate. etc.

The antiperspirant compositions can be formulated into topicalantiperspirant and/or deodorant formulations suitable for application toskin, illustratively a stick, a gel, a cream, a roll-on, a soft solid, apowder, a liquid, an emulsion, a suspension, a dispersion or a spray.The composition can comprise a single phase or can be a multi-phasesystem, for example a system comprising a polar phase and an oil phase,optionally in the form of a stable emulsion. The composition can beliquid, semi-solid or solid. The antiperspirant and/or deodorantformulation can be provided in any suitable container such as an aerosolcan, tube or container with a porous cap, roll-on container, bottle,container with an open end, etc.

The compositions can be used in a method to reduce sweating by applyingthe composition to skin. In certain embodiments, the application is toaxilla. Also, the compositions can be used to kill bacteria bycontacting bacteria with the composition comprising the zinc complexesof the present disclosure. In embodiments, other additives for killingbacteria can also be employed in the compositions of the presentdisclosure. Various suitable additional antimicrobial additives areknown in the art.

Thus the present disclosure provides (i) a method for controllingperspiration comprising applying to skin an antiperspirant effectiveamount of a formulation of any embodiment embraced or specificallydescribed herein; and (ii) a method for controlling odor fromperspiration comprises applying to skin a deodorant effective amount ofa formulation of any embodiment embraced or specifically describedherein.

The present disclosure is further illustrated through the followingnon-limiting example(s).

EXAMPLES Examples 1 to 6

Zinc lactate and sodium hexametaphosphate (SHMP) were mixed to targetmol ratios and then diluted to a total of 10 g solution with DI water.Reagents were weighed with an electronic scale having, an ±0.0001 gaccuracy. Target mole ratios for Examples 1 to 6 are as shown in Table 1below. The mixtures were sonicated and the different behaviors of zincphosphate at the different mole ratios were recorded. After beingsonicated, samples of the example formulations 1 to 6 were aged in anoven at 50° C. for 17 hours. Other samples of the example formulations 1to 6 were aged at room temperature for 6 days. The results of thesetests are shown in Table 1.

TABLE 1 P:Zn Observation SHMP Mole After After After 6 Example ZnLac (g)(g) Ratio Total (g) Sonicated Oven days RT 1 0.25 0.092 1 10.012 Cloudy,Precip Precip precip. 2 0.25 0.46 5 10.005 Cloudy, Precip Precip precip.3 0.25 0.92 10 10.62 Clear Precip Precip 4 0.25 1.84 20 10.129 ClearClear Clear 5 0.25 3.68 40 10.325 Clear Clear Precip 6 0.25 5.52 6010.006 Amorphous Precip Precip precip.

After sonication, Examples 3, 4 and 5 were clear, indicating that asoluble zinc polyphosphate complex had formed in each of those samples.Samples 4 and 5 remained clear after aging in the oven at 50° C. It wasfound that after a week, only the formulation of Example 4 stayedsoluble while all the other samples precipitated.

Based on these results, it was determined that zinc complex made withzinc lactate and sodium hexametaphosphate became soluble, resulting inthe solution becoming clear, when combined at mole ratio of P:Zn ofapproximately 20:1 (reagent mass ratio of 2.5% w/w zinc salt per 18.41%w/w SHMP) or approximately 21:1 (reagent mass ratio SHMP:ZnL=8:1).

Because the average chain length of the zinc polyphosphate complex is23P and mole ratio of P:Zn is about 20:1 or 21:1, it is predicted thatfor this soluble zinc Phosphate species, 1 zinc is bonded to eachphosphate chain on average.

Examples 7 and 8

Samples of the formulation of Example 4 were mixed with protein (1%Bovine serum albumin (“BSA”)). One sample (Example 7) as heated to 37°C. and aged overnight. Another sample (Example 8) was aged at roomtemperature overnight. Both formulations were then further aged for aweek at room temperature.

The samples appeared clear prior to aging. Upon aging overnight, whiteprecipitates formed in both the formulations of Examples 7 and 8.Additional precipitates appeared to form in both samples after aging fora week. The Example 7 formulation showed more precipitates than theExample 8 formulation both after aging overnight and after a week.

Example 9

0.6247 grams of zinc lactate and 4.603 grams of SHMP were added to anaqueous solution to form 25.035 total grams of solution. Two samples, a5.7 gram sample (Example 9) and a 5.12 gram sample (control sample) ofthe solution were added to glass containers. The pH of the Example 9solution was carefully adjusted from a starting pH of 477 to a pH 7.56by adding sodium hydroxide, at which point a precipitate formed. The pHof the solution was then lowered by carefully adding hydrochloric aciduntil the precipitates dissolved completely at a pH of 7.03. This dataindicates that the aqueous soluble zinc lactate polyphosphate complexwill generate white zinc precipitates when pH is raised to above 7.

In order to determine if the Example 9 solution would precipitate atoral conditions (pH 7.4 and 37° C.) the pH of the solution was furtherdecreased from 7.03 by adding hydrochloric acid until a pH of 6.1 wasreached, and the solution was then aged overnight at a mouth condition(37° C.). Precipitates were formed and settled on the bottom of theglass container after aging. This provides strong evidence that the zinclactate and SHMP complex is a potential active for dentinalhypersensitivity relief.

Based on the above data, it is believed that the soluble zinc phosphatemixture can potentially be used in dentinal tubules mitigationtoothpaste or other oral compositions used for treating dentinalhypersensitivity. At a certain molar ratio (approximately 20P:1Zn),soluble Zinc solution can he obtained when Zinc lactate is mixed withSodium Hexametaphosphate. While not wishing to be bound by theory, it istheorized that soluble Zinc polyphosphate solution indicates that acomplex is being formed between Zn cations and phosphate anions. Whenthis soluble solution is mixed with BSA protein, it quickly starts toprecipitate and will be able to block the tubules. In addition, Zn2+will hydrolyze to amorphous zinc hydroxide to physically block thetubules.

Example 10

Examples 10 to 20 below were freshly prepared using zinc citratetrihydrate and sodium hexametaphosphate (“SHMP”) (0.009736mol Phosphorusper gram of SHMP; 69.1% P₂O₅ per gram of SHMP) at the P/ZN mole ratiosshown in Table 2. Reagents were used as received by the manufacturer.Samples were weighed using a laboratory scale (±0.0001 g) and then mixedin scintillation vials.

TABLE 2 Solution Preparation at Various Ratios P/Zn Exam- Mole ActualPercent ple Ratio Weight (g) in solution Appearance pH 10 2 0.2031 g2.00% ZnCit Solution ZnCit appears turbid 0.2062 g 2.03% SHMP SHMPpowder 9.7629 g 95.97% water water 11 3 0.2038 g 2.00% ZnCit SolutionZnCit appears turbid 0.3081 g 3.03% SHMP SHMP powder 9.6582 g 94.97%water water 12 4 0.2040 g 2.01% ZnCit Solution is ZnCit clear but 0.41124.04% SHMP appears turbid SHMP after 1 day at powder RT 9.5574 g 93.95%water water 13 5 0.2032 g 2.00% ZnCit Solution is 5.13 ZnCit clear for 10.9990 g 50% 4.91% SHMP week SHMP solution 8.9635 g 93.09% water water14 10 0.2038 g 1.98% ZnCit Solution 5.08 ZnCit remains clear 2.0402 g50% 9.89% SHMP SHMP solution 8.0710 g 88.13% water water 15 21 0.2031 g2.00% ZnCit Solution 4.99 ZnCit remains clear 2.1571 g 21.21% SHMP SHMPpowder 7.8085 g 76.79% water water 16 30 0.2036 g 2.00% ZnCit Solution4.78 ZnCit remains clear 5.9915 g 29.47% SHMP 50% SHMP solution 3.9696 g68.53% water water 17 50 0.2038 g 1.94% ZnCit Solution 4.68 ZnCitremains clear 10.2744 g 49.03% SHMP 50% SHMP solution 0 g water 49.03%water 18 55 0.2030 g 2.00% ZnCit Solution ZnCit appears turbid 5.6493 g55.57% SHMP SHMP powder 4.3134 g 42.43% water water 19 60 0.2036 g 2.00%ZnCit Solution ZnCit appears turbid 6.1621 g 60.59% SHMP SHMP powder3.8045 g 37.41% water water 20 70 0.2028 g 1.99% ZnCit Solution ZnCitappears turbid 7.1890 g 70.70% SHMP SHMP powder 2.7770 g 27.31% waterwater

As Table 2 shows, the P/Zn mole ratios spanning from above 4P/Zn tobelow 55P/Zn form a clear solution when mixed. It was concluded that acomplex forms between the zinc citrate and SHMP.

Examples 21 to 26

Examples 21 w 26 of Table 3 below were freshly prepared using zinccitrate trihydrate and sodium hexametaphosphate (“SHMP”) (0.009736 molPhosphorus per gram of SHMP; 69.1% P₂O₅ per gram of SHMP) at the P/ZNmole ratios shown in Table 3. Reagents were used as received by themanufacturer. Samples were weighed using a laboratory scale (±0.0001 g)and then mixed in scintillation vials.

TABLE 3 Solution Preparation of Low P/Zn Ratio Solutions for Aging StudyP/Zn Mole Actual Percent in Example Ratio Weight (g) solution pH 21 200.2103 g ZnCit 2.01% ZnCit 5.16 2.0539 g SHMP 19.62% SHMP powder 78.38%water 8.2067 g water 22 15 0.2102 g ZnCit 2.01% ZnCit 5.22 1.6511 g SHMP15.78% SHMP powder 8.6046 g water 82.22% water 23 10 0.2093 g ZnCit2.00% ZnCit 5.24 1.02649 g 9.80% SHMP SHMP 9.2328 g water 88.20% water24 8 0.2089 g ZnCit 2.00% ZnCit 5.26 0.8225 g SHMP 7.85% SHMP 9.4387 gwater 90.15% 25 6 0.2096 g ZnCit 2.00% ZnCit 5.18 0.6165 g SHMP 5.89%SHMP powder 9.6436 g water 92.11% water 26 5 0.2096 g ZnCit 2.00% ZnCit5.25 0.5140 g SHMP 4.91% SHMP powder 9.7432 g water 93.09% water

Examples 27 to 32 Aging Study

Two sets of samples for each of the solutions of Table 3 with a P/Znmole ratio of 20, 15, 10, 8, 6, and 5 were taken. One set of samples asaged at room temperature (about 20° C.) for a week. The other set ofsamples was aged at 37° C. for a week. The solutions aged at roomtemperature and containing a mole ratio ranging from 20 P/Zn to 6 P/Znwere stable at room temperature and remained clear throughout the agingperiod. The solution with a mole ratio of 5 P/Zn became turbid at roomtemperature and the precipitate settled to the bottom of the flask. Forthe solutions aged at 37° C., in the range of 20 P/Zn to 5 P/Zn moleratio solutions, only the 20P/Zn mole ratio solution remained stable(not turbid, without visible precipitate

Examples 33 to 38 Aging Studying With BSA

Examples 33 to 38 of Table 4 below were freshly prepared using zinccitrate trihydrate and sodium hexametaphosphate (“SHMP”) (0.009736 molPhosphorus per gram of SHMP; 69.1% P₂O₅ per aram of SHMP) at the P/ZNmole ratios shown in Table 3. The pH was adjusted using sodium hydroxideand/or hydrochloric acid. 1% by weight BSA protein was added to eachsample. Reagents were used as received by the manufacturer. Samples wereweighed using a laboratory scale (±0.0001 g) and then mixed inscintillation vials. A control sample of 1% BSA solution of DI water wasalso prepared.

TABLE 4 Solution Preparation of 1% BSA Solutions Amount of BSA Amount ofTotal Example Sample (g) Solution 33 1% BSA in 1Zn:20P 0.0200 g 2.0371 gsolution 34 1% BSA in 1Zn:15P 0.0195 g 2.0211 g solution 35 1% BSA in1Zn:10P 0.0209 g 2.0050 g solution 36 1% BSA in 1Zn:8P 0.0199 g 1.9997 gsolution 37 1% BSA in 1Zn:6P 0.0194 g 2.0021 g solution 38 1% BSA in1Zn:5P 0.0200 g 1.9976 g solution Control 1% BSA in DI water 0.0207 g2.0031 g Sample

The solutions of Table 4, having a P/Zn mole ratio of 20, 15, 10, 8, 6.and 5 and containing 1% BSA were aged at 37° C. for two days and werecompared to the control solution of 1% BSA in DI water. After aging, thecontrol sample having a 1% BSA solution of Di water did not form aprecipitate and remained clear. All of the zinc citrate and SHMPsolutions containing 1% BSA formed a precipitate.

Examples 39 to 41 Solution Preparation and Aging of 10% Saliva Solutions

Examples 39 to 42 of Table 5 below were freshly prepared using zinccitrate trihydrate and sodium hexametaphosphate (“SHMP”) (0.009736 molPhosphorus per gram of SHMP; 69.1% P₂O₅ per gram of SHMP) at the P/ZNmole ratios shown in Table 3. 10% by weight saliva was added. The amountof BSA protein shown in Table 5 was added to each sample. Reagents wereused as received by the manufacturer. Samples were weighed using alaboratory scale (±0.0001 g) and then mixed in scintillation vials. Acontrol sample of 1% BSA solution of DI water was also prepared.

TABLE 5 Amount of BSA Amount of Total Example Sample (g) Solution 39 10%Saliva in 1Zn:20P 0.2039 g 2.0037 g solution 40 10% Saliva in 1Zn:10P0.2014 g 2.0119 g solution 41 10% Saliva in 1Zn:6P 0.2130 g 2.0053 gsolution 42 Control: 10% Saliva in 0.2065 g 2.0031 g DI water

The solutions with a P/Zn mole ratio of 20. 10 and 6 containing 10%saliva from Table 5 were aged at 50° C. for two days and were comparedto the control solution of 10% saliva in DI water. The ZnCit+SHMP withsaliva solutions at 50° C. become turbid (precipitates formed) comparedto the 10% saliva control solution at 50° C., which remained relativelyclear.

Example 42

A zinc citrate trihydrate and sodium hexametaphosphate (“SHMP”)(0.009736 mol Phosphorus per gram of SHMP; 69.1% P₂O₅ per gram of SHMP)at the P/ZN mole ratio of 20 was prepared. The initial pH of the 20P/1Znratio solution was measured to be 4.95. The pH was then raised in smallincrements using NaOH. The solution remained clear at every pH incrementbelow 9.67. At pH=9.67 the solution became turbid. The pH of thesolution was then lowered using HCl. At pH=8.99, the solution was stillturbid but noticeably less turbid than at 9.67. At pH=8.56, the solutionappeared clear again.

Example 43

A zinc citrate trihydrate and sodium hexametaphosphate (“SHMP”) (0.00973mol Phosphorus per gram of SHMP; 69.1% P₂O₅ per gram of SHMP) at theP/ZN mole ratio of 15 was prepared. The initial pH of the 15P1/Zn moleratio solution was measured to be 4.93. The pH was then raised in smallincrements using NaOH. The solution remained clear at every pH incrementbelow 9.46. At pH=9,46 the solution appeared slightly turbid and atpH=9.64, the solution was even more turbid. Upon lowering this solutionusing HCl, at pH 8.74, the solution appeared clear once again.

Example 44

Because a SHMP+ZnCit solution in a 1Zn:20P mole ratio gave a clearsolution when the zinc citrate concentration in the final solution was2% by weight, the same ratio was used in the preparation of higherconcentrations of zinc citrate in zinc citrate+SHMP solutions, as shownin Tables 6 and 7.

TABLE 6 3.0% Zinc Citrate Actual Percent pH Upon Mass (g) (%)Preparation SHMP 2.0546 29.38% 4.87 Water 4.7286 67.62% ZnCit 0.20943.00%

TABLE 7 2.5% Zinc Citrate Actual Percent pH Upon Mass (g) (%)Preparation SHMP 2.0548 24.53% 4.92 Water 6.1149 72.98% ZnCit 0.20852.49%

Both the 2.5% and 3.0% by weight solutions of Tables 6 and 7 appearedturbid after aging at room temperature (about 20° C.) for one day. Since2% Zinc Citrate gives a clear solution and other solutions with greaterconcentrations of zinc citrate appear turbid. This data suggests thatthe highest amount of Zinc Citrate that can be added to the SHMPsolution is between 2% to 2.5% in the final solution if it is desired toavoid precipitation of the complex.

The novel complexes formed from insoluble Zinc Citrate trihydrate andpoly phosphate (SHMP), as described in the above examples, present asclear solutions at various P/Zn mole ratios ranging from above 5P/Zn tobelow 55P/Zn. After aging for a week at room temperature, the solutionsthat remained stable ranged between 6 P/Zn and 20 P/Zn. Upon aging thevarious ratios at 37° C. for a week, the 20 P/Zn mole ratio solutionremained completely clear. This indicates that at higher temperatures(e.g., biological temperatures, such as human body temperature),complexes of the present disclosure having a mole ratio of about 20P/1Zncan remain soluble. Further adjustment of the pH of such a solution, aswell as that of the 15P/1Zn ratio solution, indicates that the solutionremains clear even at a high pH of around 9.6. The stability of thesolution at a high pH renders it compatible with formulations possessinga neutral or high pH. The above data showed that the highest amount ofzinc citrate that can be loaded into the 20P/Zn mole ratio solutionprior to precipitation ranges between 2%-2.5% of the trihydrate powderat a pH of approximately 4.9 and room temperature.

It was also found that when zinc citrate is mixed with SHMP in a ratiogreater than 1Zn:6P and less than 1Zn:55P, the resulting solutionappears clear with a pH of 5±0.2. Furthermore, it is reported that uponaddition of BSA and saliva, separately, the zinc citrate-phosphatecomplex forms a precipitate. Upon addition of saliva to the solutions at50° C. ranging from 6P/Zn to 20P/Zn, all of the solutions became turbid,indicating the formation of a precipitate upon interaction with saliva.Lowering the pH back produced a clear solution, once again.

Based on this data, it is believed that the soluble complexes of thepresent disclosure will allow delivery of precipitate to block dentintubules and thereby provide sensitivity relief when used in oralcompositions. Further, BSA in the above experiments simulates sweatproteins. Based on the data, it is believed that the complexes of thepresent disclosure can diffuse into sweat glands and precipitate incombination with protein to block the sweat ducts of a user, therebypreventing or reducing the amount of sweat from coming out skin whenused as an active ingredient in antiperspirants. In essence, thesolubility characteristics of the zinc complex allows it to readilydiffuse into dentin tubules or sweat glands and precipitate, therebyblocking the tubules or glands. The solubility can also allowformulation into liquid products, such as mouthwash. Additionally, thesoluble Zinc complex can potentially be used to make transparentproducts.

What is claimed is:
 1. An oral care composition, comprising: a solublezinc polyphosphate complex, made by combining zinc citrate and sodiumhexametaphosphate, and water; wherein the relative amounts of zinccitrate and sodium hexametaphosphate to provide the soluble zincpolyphosphate complex with a phosphorus to zinc mole ratio of 20:1. 2.The oral care composition of claim 1, wherein the zinc polyphosphatecomplex has an average of about 1 zinc atom.
 3. The oral carecomposition of claim 1, wherein the zinc polyphosphate complex has aproperty of becoming insoluble at a pH ranging from about 5.5 to about6.5.
 4. The oral care composition of claim 1, wherein the zincpolyphosphate complex is insoluble at a pH below 5.5 in the presence ofsalivary proteins.